The Jewish new year celebration, Rosh Hashanah, began Sunday night, and for most observant adherents it is meant to kick off a period of often personal reflection.

But one religious leader took the holiday as an opportunity to send a message to a man who he said was a former congregant: presidential adviser Stephen Miller.

In a fiery sermon that has now been covered by news outlets around the world, Rabbi Neil Comess-Daniels of Beth Shir Shalom, a synagogue in Santa Monica, California, where Miller grew up, denounced Miller for his role in the proposal that resulted in the family separation crisis at the border, questioning how his values diverged so sharply from the congregation's.

"The actions that you now encourage President [Donald] Trump to take make it obvious to me that you didn't get my or our Jewish message," Comess-Daniels said. "That notion is completely antithetical to everything I know about Judaism, Jewish law and Jewish values."

Comess-Daniels said Miller's family belonged to the synagogue when Miller was about 9 or 10 years old; Miller attended Hebrew School there and his younger sister later had her bat mitzvah there, he said. It was not clear how long the family was involved with the synagogue. The White House did not return a request for comment.

Comess-Daniels framed Miller's role in the White House as a potential failure of his synagogue and its teachings.

"What is troublesome to me is that some of my colleagues and others are concerned what I might have taught you when you were a member of our community," Comess-Daniels said.

More than 2,600 children were separated from their families after they crossed the U.S.-Mexico border this year, the result of a change in federal practice to charge all undocumented immigrants crossing the border with crimes. As The Washington Post has previously reported, Miller, who is considered a hard-liner on immigration, was one of a small circle of Trump administration members who played a crucial role in making the proposal actionable. The separations were halted June 20 amid multiple lawsuits, but hundreds of children remain separated from their families in government-funded shelters.

Comess-Daniels pointed to the long history of Jews as refugees and said that the practice violated fundamental Jewish tenants.

"From the Jewish perspective, the parent-child relationship is sacrosanct," he said. "Disrupting it is cruel. Mr. Miller, the policy you helped to conceive and put into practice is cruel."

His comments echoed those made by Miller's uncle David Glosser, who in August penned a scathing op-ed that noted the family's history of immigration to the United States - the family's patriarch, Wolf-Leib Glosser, landed at Ellis Island after fleeing violence in Eastern Europe - and accused Miller of being a hypocrite.

"I have watched with dismay and increasing horror as my nephew, who is an educated man and well aware of his heritage, has become the architect of immigration policies that repudiate the very foundation of our family's life in this country," Glosser wrote.

Comess-Daniels compared the historical experiences of Jewish people to the current plight of refugees worldwide.

"We Jews have chosen our history to be our mandate," he said. "We choose to remember and underscore that the quintessential experience of the Jewish people is both the slavery in and the exodus from Egypt. We are all refugees Mr. Miller."

Comess-Daniels also referenced the Holocaust, speaking about children who perished, such as Anne Frank or others who were shepherded out of Germany while their parents were in concentration camps through rescue efforts like Kindertransport.

"These were Jewish unaccompanied minors," he said, drawing a parallel with the immigrant children who have come across the border in recent years to flee violence in Central America. "Honestly Mr. Miller, you've set back the Jewish contribution to making the world spiritually whole through your arbitrary division of these desperate families at our southern border."

The sermon, which was filmed in a live stream on the congregation's Facebook page, made a splash, drawing coverage in The Guardian, among other outlets. Comess-Daniels explained to CNN on Tuesday his decision to rebuke Miller.

"I chose to speak out on it because it's something that kind of sticks in the craw of the Jewish people, because we've been refugees under so many conditions during so many times in history," he said. "And ultimately that we need to make clear to anyone that's listening, certainly a senior adviser to the president, is what our values are, what our morals are, and when they're transgressed, we need to say something about it."

Miller's parents still live in Santa Monica but they are no longer members of the synagogue, according to The Guardian.